DATA: STRING_1(20) TYPE C, STRING_1_TYPE(4) TYPE C,
      STRING_2(20) TYPE C, STRING_2_TYPE(4) TYPE C,
      STRING_3(20) TYPE C, STRING_3_TYPE(4) TYPE C.

STRING_1 = '12345678901234567890'.
STRING_2 = 'abcdefg우리나라만세z'.
STRING_3 = 'abcdAAA34557azzidfll'.

CALL FUNCTION 'NUMERIC_CHECK'
     EXPORTING
          STRING_IN = STRING_1
     IMPORTING
          HTYPE     = STRING_1_TYPE.

CALL FUNCTION 'NUMERIC_CHECK'
     EXPORTING
          STRING_IN = STRING_2
     IMPORTING
          HTYPE     = STRING_2_TYPE.

CALL FUNCTION 'NUMERIC_CHECK'
     EXPORTING
          STRING_IN = STRING_3
     IMPORTING
          HTYPE     = STRING_3_TYPE.

STRING_1_TYPE : NUMC
STRING_2_TYPE : CHAR
STRING_3_TYPE : CHAR